Effects of denitrification on the distributions of trace gas abundances in the polar regions: a comparison of WACCM with observations
Effects of denitrification on the distributions of trace gas abundances in the polar regions: a comparison of WACCM with observations
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DOI：
10.5194/acp-23-6849-2023
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发表时间：
2023-06
影响因子：
6.3
通讯作者：
M. Weimer;D. Kinnison;C. Wilka;S. Solomon
中科院分区：
文献类型：
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作者：
M. Weimer;D. Kinnison;C. Wilka;S. Solomon
抽象的。极地平流层云（PSC）在平流层的极地化学中起着关键作用。硝酸三水合物（NAT）颗粒已被证明会导致平流层下部的反硝化作用。虽然大的NAT粒子（NAT“岩石”）的存在已经被许多测量所证实，特别是在北方半球（NH），但大多数当前的化学气候模式使用简化的参数化，通常基于南半球的评估，那里的极涡足够稳定，NAT岩石的解释并不像北半球那样重要。在这里，我们评估的概率密度函数的各种气体物种在极涡使用这样一个模型，全大气社区气候模型（WACCM），并比较这些测量的迈克尔逊干涉仪被动大气探测机载环境卫星（MIPAS/Envisat）和两个臭氧探测站的一系列年，在两个半球。使用MIPAS和WACCM分布之间的最大差异作为一致性的度量，我们发现在两个半球的MIPAS期间几乎所有春季，当NAT数密度从该模型中使用的标准值10−2降低到5×10-4 cm−3时，HNO 3的一致性更好。ClONO_2和O_3的分布受NAT浓度的影响不大。WACCM和臭氧探测器之间的平均差异支持需要减少模型中的NAT数密度。因此，本研究建议使用5×10-4 cm−3的NAT数密度用于WACCM的未来模拟。
Abstract. Polar stratospheric clouds (PSCs) play a key role in the polar chemistry of the stratosphere. Nitric acid trihydrate (NAT) particles have been shown to lead to denitrification of the lower stratosphere. While the existence of large NAT particles (NAT “rocks”) has been verified by many measurements, especially in the Northern Hemisphere (NH), most current chemistry–climate models use simplified parameterizations, often based on evaluations in the Southern Hemisphere where the polar vortex is stable enough that accounting for NAT rocks is not as important as in the NH. Here, we evaluate the probability density functions of various gaseous species in the polar vortex using one such model, the Whole Atmosphere Community Climate Model (WACCM), and compare these with measurements by the Michelson Interferometer for Passive Atmospheric Sounding onboard the Environmental Satellite (MIPAS/Envisat) and two ozonesonde stations for a range of years and in both hemispheres. Using the maximum difference between the distributions of MIPAS and WACCM as a measure of coherence, we find better agreement for HNO3 when reducing the NAT number density from the standard value of 10−2 used in this model to 5×10-4 cm−3 for almost all spring seasons during the MIPAS period in both hemispheres. The distributions of ClONO2 and O3 are not greatly affected by the NAT density. The average difference between WACCM and ozonesondes supports the need to reduce the NAT number density in the model. Therefore, this study suggests using a NAT number density of 5×10-4 cm−3 for future simulations with WACCM.